Anecdotally, there are reports the person is more uninhibited and sexually insistent than they are when awake. And it’s not great sex. More automated, and robotic, experts say.

Or as Barilla’s wife said: “It was silent throughout ... I did not like it.”

In one BBC article, a woman recalled two incidents with a man who unknowingly had sexsomnia (and thus didn’t remember either encounter).

One night, he “began thrusting at her groin in a crude, unsensual kind of way”.

During a later episode, he tried having penetrative sex through her underwear.

She considered leaving him, but then started asking some questions, genuinely puzzled by the out-of-character behaviour he told her he had no memory of, and his devastation that he had upset and hurt her.

A sleep clinic ultimately revealed he had sexsomnia.

THERE’S NOT MANY SEXSOMNIACS

Sexsomnia is quite rare compared to conditions like sleepwalking.

Sleepwalking affects about one in 25 kids, but 66 per cent of them grow out of it.

Sexsomnia, most often experienced by males, is much less common.

In fact, in 20 years of conducting sleep clinics, Victoria University associate professor Gerald Kennedy has “only seen four or possibly five genuine cases”.

“People who suffer from sexsomnia are those who have an extended history of sleepwalking or other unusual sleep behaviours,” he told Vice.

“It’s a real condition where someone can have sex without realising or wanting it and not remember anything.”

Not many people, even doctors, know about it. It was added in 2013 to the Diagnostic and Statistical Manual of Mental Disorders.

A 2003 Toronto Western Hospital study found that 11 per cent of its male sleep-centre patients experienced sexsomnia, compared to just four per cent of female patients did.

Some factors think the numbers of sufferers are bigger, but those incidents aren’t reported because sufferers are either too embarrassed to report it, or just don’t remember it.

THEY SLEEP, RATHER THAN SLEEPWALK, AMONG US

The idea that sexsomniacs are sleepwalking their way, zombie-like, to have their way is far-fetched.

Apparently, it’s all about proximity.

“It’s not likely that the person will wander out of their bed to have sex,” Prof Kennedy said.

“It’s more likely that when they’re lying in bed with somebody they’ll have a sexsomnia episode and have sex in their sleep.”

And therein, lies the problem. And many victims. And several court cases.

“If you do have it and you share a bed with someone, and they wake up to you sexually assaulting them, then they’ll probably have some complaints,” said Prof Kennedy.

“So you have a duty of care towards them. It’s like if someone had AIDS, they have to tell people they have it if they’re going to have sex with them so they can take the appropriate precautions.”

For sexsomnia to fly legally, a documented or diagnosed history helps.

Prof Kennedy warns also it may not mean offenders escape charges: “If I get drunk and I kill someone, I’m probably still going to be found guilty,” he said.

“But it’s going to affect the sentencing side of it. If I knew I had sexsomnia, and I sexually assaulted someone in my sleep, the judge would probably say: you knew you had this and you didn’t warn the people around you. Therefore you would probably still be found guilty, but be punished more lightly.”

In 2013, sexsomnia In Australia in 2014, amid concerns some sex offenders were feigning the condition to use it as a defence in court, the Australian Sleep Association moved to ensure doctors called to give expert testimony were well across the condition.

“It’s a wake-up call that there are a lot more of these cases in the public media and therefore it’s highly likely that this sort of defence — of sexsomnia and automatism — will be coming their way,” Woolcock Institute of Medical Research medical director Dev Banerjee told Fairfax.

It’s not great sex. More automated, and robotic, experts say. Picture: iStockSource:Supplied

The 48-year-old entered the bedroom of a guest at his home at Nhulunbuy in northeast Arnhem Land in the early morning of June 2007 and got into the 21-year-old’s bed.

Mr Spencer, who claimed he had no recollection of the event, was accused of gross indecency and sexual intercourse without consent.

But his lawyer argued Mr Spencer was asleep at the time and depressed over his marriage breakup.

In the UK it has become such a regular defence in sex assault trials that prosecutors now sometimes don’t even bring a case to trial if the defendant can prove they suffer from the condition.

Last month, The Irish Times forecast the defence would increasingly come into play in Ireland after the office of the Director of Public Prosecutions said it would not proceeding with the trial of a 31-year-old man accused of raping his friend after a night out while they shared a bed.

It was to be the third trial in the case, the publication said.

The first trial collapsed for legal reasons while the second resulted in a hung jury.

During those trials, the accused maintained he may have had sex with the woman but that it happened as a result of him suffering from sexsomnia,

TREATMENT

While the cause of sexsomnia is still unknown, and the episodes are considered random, researchers think that people are triggered into them when there’s a disruption in the brain as it moves between deep sleep cycles.